• Smart Structures and Systems
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• 제20권6호
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• pp.641-656
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• 2017

The effects of vertical component of earthquakes on torsional amplification due to mass eccentricity in seismic responses of base-isolated structures subjected to near-field ground motions are studied in this paper. 3-, 6- and 9-story superstructures and aspect ratios of 1, 2 and 3 have been modeled as steel special moment frames mounted on Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratios. Three-dimensional linear superstructures resting on nonlinear isolators are subjected to both 2 and 3 component near-field ground motions. Effects of mass eccentricity and vertical component of 25 near-field earthquakes on the seismic responses including maximum isolator displacement and base shear as well as peak superstructure acceleration are studied. The results indicate that the effect of vertical component on the responses of asymmetric structures, especially on the base shear is significant. Therefore, it can be claimed that in the absence of the vertical component, mass eccentricity has a little effect on the base shear increase. Additionally, the impact of this component on acceleration is remarkable so the roof acceleration of a nine-story structure has been increased 1.67 times, compared to the case that the structure is subjected to only horizontal components of earthquakes.

• 대기
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• 제22권2호
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• pp.259-265
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• 2012

This study investigates the reason why the barotropic vorticity structure prevails vertically in response to the enhanced convection associated with the boreal summer intraseasonal oscillation over the central Indian Ocean. The relative vorticity tendency analysis for a 2.5-layer simplified model demonstrates that the barotopic vorticity structure is predominant due to the following two factors: 1) vertical easterly shear on the meridional gradient of barotropic divergence (which induces generation of barotropic vorticity twice larger than that of baroclinic vorticity); and 2) vertical easterly shear on the meridional gradient of baroclinic divergence (which appears only in relation to the generation of barotropic vorticity). The percentage of contribution by each term to barotropic and baroclinic vorticity tendency equations is presented.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.149-156
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• 1993

Precast concrete (P.C.) large panel structures have usually weaker stiffness at joints than that of monolithic in-situ reinforced concrete structures. But structural designers do not in general take into account this characteristics of P. C. large panel structures and use the same analytical models as for the monolithic structure. Therefore, the results of analysis obtained by using these models may be quite different from those actually occuring in real P.C. structure. In this study, the change in force and stress distribution and deflections of structure caused by applying lower shear stiffness at vertical joints are investigated through trying several finite element modeling schemes specific for P.C. structures. Finally, for engineers in practice. a simplified model, which takes account of the effect of lower shear stiffness at vertical joints, is proposed with the understanding on possible amount of errors.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.279-286
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• 1997

The objective of this paper is to investigate the effects of the rocking motion and the vertical natural frequency of a seismically isolated structure using LRBs. The governing equations of motion of the rigid body structure, which consider a large rocking motion, are derived. For the mathematical model of LRB, the horizontal stiffness equation based on Haringx's theory is used. From this paper, as decreasing the vertical natural frequency, the rocking responses increase and the horizontal isolation frequency and its earthquake responses are severely affected.

• 공학기술논문지
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• 제11권4호
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• pp.237-243
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• 2018

The purpose of this study is to develop a vertical wind turbine with antenna structure in microgird environment. Computational fluid dynamics (CFD) was used to calculate the basic aerodynamic performance. The pressure resulted from CFD analysis has been mapped on the surface of wind turbine as load condition and the Fluid Structure Interaction (FSI) was applied. The stability of the wind turbine was confirmed by checking the deformation and internal stress of wind turbine by wind force.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.30-34
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• 2005

This study shows the lasing characteristics of InGaAs/InGaAsP multiple-quantum-well waveguide-type depleted optical thyristor (DOT) using the vertical window. The measured switching voltage and current are 3.36 V and 10 ㎂, respectively. The lasing threshold current is 131 mA at 25 ℃. The output peak wavelength is 1570 nm at a bias current of 1.22 Ith and there is not input signal anymore in the output port. The vertical injection depleted optical thyristor - laser diode (VIDOT-LD) using the vertical-injection structure shows very good isolation between input and output signal.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1242-1247
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• 2011

This study investigates vertical vibration control method for railway structure by using vertical vibration control device. The device consists of high stiffness polyurethane spring and friction damper recognized by National Center for Earthquake Engineering Research of USA for durability. To confirm the capacity of vertical vibration control, at first, behavior equation is established by considering correlation among the components. Then, hysteresis curve is drawed from behavior equation. By considering both dynamic behaviors and material nonlinearities, more reasonable behavior of the device can be simulated. After that, the Validity of the vibration control trend is proved by FEM(Finite Element Method).

• ALGAE
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• 제18권4호
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• pp.301-309
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• 2003

Community structure and vertical distribution of benthic marine algae were investigated in the intertidal and subtidal rocky shore of Samyang, Jejudo Island. The total number of 62 algal species composed of 6 Cyanophyta, 6 Chlorophyta, 19 Phaeophyta, and 31 Rhodophyta were observed. The dominant species were melobesioidean algae, Sargassum thunbergii, Hizikia fusiformis, and Ulva pertusa in the intertidal zone and melobesioidean algae, Ulva pertusa, Corallina spp., and Undaria pinnatifida in the subtidal zone. The vertical algal distribution was represented by the melobesioidean algae in the whole rocky shore, Caulacanthus ustulatus in the upper intertidal zone, Sargassum thunbergii and Hizikia fusiformis in the middle and lower zone, Ulva pertusa in the lower zone and Ulva pertusa, Corallina spp., and Undaria prinnatifida in the subtidal zone. The composition of dominant species and pattern of the vertical distribution of algae in the present study were significantly different from the previous reports. Especially, distribution of crustose coralline algae was significantly extended.

• Structural Engineering and Mechanics
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• 제10권6호
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• pp.603-619
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• 2000

Analysis of a framed structure for vertical vibration requires a lot of computational efforts because large number of degrees of freedom are generally involved in the dynamic responses. This paper presents an efficient modeling technique for vertical vibration utilizing substructuring technique and super elements. To simplify the modeling procedure each floor in a structure is modeled as a substructure. Only the vertical translational degrees of freedom are selected as master degrees of freedom in the inside of each substructure. At the substructure-column interface, horizontal and rotational degrees of freedom are also included considering the compatibility condition of slabs and columns. For further simplification, the repeated parts in a substructure are modeled as super elements, which reduces computation time required for the construction of system matrices in a substructure. Finally, the Guyan reduction technique is applied to enhance the efficiency of dynamic analysis. In numerical examples, the efficiency and accuracy of the proposed method are demonstrated by comparing the response time histories and the analysis time.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.537-542
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• 2014

The three-dimensional (3-D) NAND flash structure with fully charge storage using edge fringing field effect is presented, and its programming characteristic is evaluated. We successfully confirmed that this structure using fringing field effect provides good program characteristics showing sufficient threshold voltage ($V_T$) margin by technology computer-aided design (TCAD) simulation. From the simulation results, we expect that program speed characteristics of proposed structure have competitive compared to other 3D NAND flash structure. Moreover, it is estimated that this structural feature using edge fringing field effect gives better design scalability compared to the conventional 3D NAND flash structures by scaling of the hole size for the vertical channel. As a result, the proposed structure is one of the candidates of Terabit 3D vertical NAND flash cell with lower bit cost and design scalability.